Created by StemPy LabAssertion (A): Water crosses the plasma membrane by active transport, from a lower to a higher concentration of water. Reason (R): Active transport uses ATP to move ions or molecules against their concentration gradient, as in the pump.
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← Chemical studies show that the membrane of a human erythrocyte has about 52 per cent protein and 40 per cent lipid. Which statement about the cell membrane is correct?Read the following statements about the nucleus and the chromosomes. (i) The outer membrane of the nuclear envelope usually stays continuous with the endoplasmic reticulum and bears ribosomes. (ii) Nuclear pores let RNA and protein molecules move in both directions between the nucleus and the cytoplasm. (iii) Chromatin contains DNA, some basic proteins called histones, some non-histone proteins and also RNA. (iv) In an acrocentric chromosome, the centromere lies exactly at one end of the chromosome. (v) Larger and more numerous nucleoli are present in cells that are actively carrying out protein synthesis. (vi) A single human cell has about 2 m of DNA, shared among 23 chromosomes. How many of the statements above are correct? →
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